厚桩承台承载力的试验研究

EXPERIMENT AND RESEARCH ON THE BEARING CAPACITY OF THICK PILE CAP

为探讨厚桩承台的合理设计计算方法，本文完成了７５个厚桩承台试件的模型试验，包括两桩台、三桩台、四桩台及六桩台试件。所有三、四、六桩厚承台试件破坏属于冲剪破坏，两桩台试件中，部分发生剪切破坏，部分发生弯曲破坏。基于对试验结果的分析，揭示了厚桩承台的破坏模式和传力机理，指出了厚极承台的受力特性不同于一般桩台，它的极限承载力常由其受冲剪承载力所控制，且传力模式是一空间桁架体系。本文提出了二、三、四及六桩厚承台的受冲剪承载力和配筋的回归公式及设计公式，利用本文建议的受冲剪承载力计算公式得到的承台厚度比按常规设计方法得到的减少了３０％－４０％。

In order.to provide a reasonable design method for thick pile cap, a seriesof test on 75 thick pile cap models with two, three, four and six piles has been carriedout.All of the models with three, four and six piles failed in punching shear, while fortwo-pile caps,some failed in shear, the others in tension. Based on the test results,the failure model and load transfer mechanism are presented. It is proved that the behavior of thick pile cap is different from that of ordinary pile cap, and the bearing capacity of thick pile cap is usually controlled by its punching shear strength and itsload transfer path is approximately treated as space truss.The formulas including theregression equations and design formulas for punching shear strength and new steel ratio of thick pile caps with two, three, four and six piles are proposed. Compared withthat obtained by current design procedure, the depth of pile cap obtained in this paper is reduced by 30-40 percent.